The present invention relates to an air conditioner having a plurality of indoor units and an operating method of the air conditioner, and, more particularly, to a system for efficiently performing a combined cooling/heating operation where one indoor unit is operated under the cooling operation, while another indoor unit is operated under the heating operation.
In, for example, Japanese Patent Publication No. 61-45145, for example, a conventional air conditioner is designed for bringing a plurality of indoor units into the cooling or heating operation by selectively changing the direction of flow of refrigerant. In the conventional air conditioner, an inlet piping line of the outdoor unit under the cooling operation can also be coupled to an outlet piping line of at least one indoor unit via a bypass pipe to branch a portion of high-pressure coolant gas for effecting the heating operation of another given indoor unit during the cooling operation. By utilizing the bypass pipe to pass a portion of the liquid refrigerant at an outlet of at least one indoor unit under the heating operation toward another given indoor unit, it is further possible to effect the cooling operation of the given indoor unit during the heating operation.
In the the above-described prior art, construction the indoor unit operated in a reverse mode, e.g., the indoor unit brought into the heating operation when air-cooling is operating under operation as a main mode, is coupled to the outdoor unit in parallel during the cooling/heating combined operation. Therefore, the refrigerant from a compressor is not properly distributed and tends to flow into the outdoor unit, in a larger amount so that the indoor unit operated under a reverse mode is supplied with the refrigerant at a reduced flow rate. This may lead to performance reduction of the unit and hence a reduction in air-conditioning.